Hi Folks,
I've been reading about Farnsworth and multipactors. The patents all make it clear that the energy source is the power supply, and they're not OU devices.
However, I've been thinking about how the electrons fly *past* the anode in the the Crookes Tube: (
http://en.wikipedia.org/wiki/Crookes_tube)
...and was wondering if it's possible to use the principle to use a small current to drive a larger current.
I would appreciate it if anyone could tell me why this would *not* be OU, so I don't end up wasting money on parts for a build...
I've done a diagram, attached below. It is a bit complex, but I'll try to explain it simply:
Physical Construction - It's a glass tube, evacuated to a high-ish vacuum.
- There are 2 standard bare electrodes - made of a metal grid - at each end of the tube. Labelled 'Powered Grid'.
Cathode on left, anode on right.
- Behind each grid, is a second grid, the 'Passive Grid', which is connected to the output collector plates.
The passive grid is charged to the opposite polarity of the powered grid by induction and by the collector.
It's made of insulated wire, or there's a strong dielectric between it and the powered grid. (To prevent spark-over)
It's there to provide an electric field which will 'trap' the electrons (or +ve ions)
It makes the collector area a faraday cage - so the charge is not deflected away from the collector plates
- The collector plates at the end are bare metal. They're marked as 'Out' on the diagram.
- The Secondary Emissive Surface (2ES) is at the center of the tube
It's bare metal, and it's earthed through a resistance.
Ideally all electrons coming from the cathode, and all +ve ions from the anode, will strike it's surface somewhere - and cause more electrons to be emitted.
Principle of OperationWhen a high voltage is applied across the input terminals:
1) Electrons are emitted from the cathode. (Because positive ions hit it's surface... etc.)
2) They are accelerated towards the anode and quickly reach very high speed.
3) They hit the Secondary Emissive Surface (2ES) - and release more electrons.
4) They are again accelerated towards the anode.
5) Some hit the anode, and complete the power-in circuit. So the tube would just look like a small resistance to the power circuit.
6) The majority of the electrons, however, fly past the anode and hit the collector.
7) The collector is charged -ve, and current flows through the LOAD A back to the central 2ES
8] The opposite happens as regards +ve charged ions... They move to the collector on the left, and power LOAD B
Notes - Some charge could be lost in the 2ES by neutralisation of charges - it depends a lot on the speed of the incoming particles.
- I think it has to have 2 separate loads to work because the circuit has to complete back in the middle... Not sure about that...
Any assistance gratefully received.
Regards, Tim